Earthquakes Top Cause of Natural Disaster Deaths

Action Points

Note that worldwide, earthquakes are the most common cause of deaths from natural disasters.

Note that morbidity and mortality tends to present in three phases. First are catastrophic injuries at the time of the earthquake which cause immediate deaths. Others die quickly within the first several hours after the event with subdural hematomas, liver or spleen lacerations, and pelvic fractures, and these might be saved with prompt treatment. A third peak of deaths occurs days to weeks later associated with sepsis, multisystem organ failure, and DIC.

Note also that crush syndromes are common and about half these patients develop acute renal failure and half of those require dialysis.

The death toll in last month's quake in Turkey stands as testimony to the devastation earthquakes -- responsible for nearly 60% of deaths from natural disasters worldwide -- can cause.

The 7.2-magnitude temblor in Turkey killed an estimated 582, adding to the 780,000 quake-related deaths over the past decade.

Roughly three times that number likely suffered nonfatal injuries from some of the worst earthquakes on record, Susan A. Bartels, MD, and Michael J. VanRooyen, MD, both of the Harvard Humanitarian Initiative in Boston, reported online in The Lancet.

Many of the deaths stemmed from brain or spinal cord trauma, followed by another round of deaths in the first several hours from injuries such as subdural hematomas, liver or spleen lacerations, and pelvic fractures.

A third peak in mortality after an earthquake occurred in the days and weeks afterward from sepsis, multisystem organ failure, and disseminated intravascular coagulation from crush injuries.

These findings came from review of 123 articles on earthquake-related morbidity and mortality in the medical literature from 1990 to 2010, though many had only anecdotal data.

Massive earthquakes, like the 9.0 that hit Japan in March and the 9.1 in Indonesia that caused a deadly tidal wave in 2004, can have a mortality rate of 1% to 8%, with a ratio of one death to three injured survivors across many studies.

Broken bones were reported as open fractures in 11% to 54% of cases and complicated by neurovascular injury in 6%. More than one-third were multiple breaks, with bones frequently in three or more pieces.

Crush injuries with systemic complications occurred at a rate of about 2% to 15% after major earthquakes.

Because resulting acute kidney problems can be lethal, people pulled from the rubble should be triaged with urine dipsticks to check for myoglobin and subclinical rhabdomyolysis, and they should receive aggressive fluid resuscitation despite initially normal vital signs.

Whether to cut fibrous connective tissue to relieve some of the internal pressure from crush injuries is controversial. Some argue that it improves circulation and reverses muscle necrosis, but others see such possible benefits outweighed by the infection risk.

Amputation of crushed limbs also is controversial, Bartels and VanRooyen noted in the paper.

"Because necrotic tissue can release large amounts of myoglobin, potassium, and tissue thromboplastin, retention of a non-salvageable limb can be life-threatening," they explained. "Necrotic tissue can also serve as a nidus for infection and sepsis."

One report concluded that even severely crushed limbs can recover full function, so amputation should be reserved for cases when a limb is already almost completely severed or when a trapped limb puts the patient's life in jeopardy.

"Realistically, the correct approach to amputation will probably be dependent on the specific setting and local context," the reviewers suggested, pointing to factors like surgical capacity, number of causalities, and types of injuries sustained in a quake.

Aside from the immediately apparent injuries, heart attacks have been seen to rise in the weeks after an earthquake. After the Northridge, Calif., quake in 1994, acute myocardial infarctions were up 35% compared with the prior week.

Arrhythmias, strokes, and even blood pressure have been shown to rise afterward as well in various studies, perhaps due in part to stress and to interruptions in access to medications.

Interruption in the supply of water and sanitation services, along with overcrowding in shelters after quakes, can also bring on epidemics of respiratory and water-borne illness, as with the cholera outbreak after the major quake in Haiti.

Acute stress disorder is common after an earthquake, often followed in the weeks after by depression.

But post-traumatic stress disorder was generally less common after natural disasters than after other types of disasters, with a frequency reported at 3.3% to 81% after earthquakes.

Children and the elderly are especially vulnerable populations, the reviewers noted.

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